Ocular: Orbital And Ocular Innervation II Flashcards
Saccades
Quick, conjugate eye movements
Right frontal eye fields (FEF) initiates saccade towards the _________________ side
Contralateral side (leftwards)
Internuclear opthalmoplegia (INO)
-lesion of the MLF = INO
-adduction deficit on the side of the MLF lesion
In a right INO:
-OD cannot adduct
-OS is dissociated nystagmus when it abducts
Left 1 1/2 syndrome
Lesion of the left CN 6 nucleus, the left MLF and often the left PPRF (vice versa for right one and a half)
PPRF is in close proximity to CN6 nucleus so…
Both are typically affected by the same lesion simultaneously
Trigeminal sensory pathway
-1st order neurons synapse at the trigeminal nucleus
-2nd order neurons decussates at the medulla and then ascends to the thalamus via the ventral trigeminothalamic tract
-3rd order neurons project to somatosensory cortex
-NO SYNAPSES at the trigeminal ganglion but instead at he trigeminal spinal nucleus caudalis
Trigeminal sub-nuclei
-principal sensory nucleus
-mesencephalic nucleus
-spinal nucleus
Principal sensory nucleus is responsible for…
Tactile information to that region
Mesencephalic nucleus is responsible for…
Proprioceptive sensory information from muscles of mastication and other muscles of the head and neck
Spinal nucleus is broken up into three spinal sub nuclei for different Trigeminal facial regions:
-pars oralis
-pars interpolaris
-pars caudalis
The regions of the spinal nucleus are responsible for…
Temperature and pain
Corneal nociceptors are in…
Interpolaris/caudalis transition zone
How can the corneal pain sensation be adjusted?
Descending pain pathways
How does V1 enter the orbit?
passing through the common tendinous ring lateral to the optic nerve, THEN courses above optic nerve
Branches off the nasociliary nerve:
-ciliary ganglion
-long ciliary nerves
-posterior ethmoidal nerve
-anterior ethmoidal nerve
-intratrochlear nerve *terminal
Ciliary ganglion has NO ____________________ and branches off ___________________
sensory synapses, short ciliary nerves
Ciliary ganglion receives input from:
-cornea
-uvea
Long ciliary nerves receive input from:
-cornea
-uvea
-conjunctiva
Posterior ethmoidal nerve receives input from:
sphenoid and ethmoid sinuses
Anterior ethmoidal nerve receives input from:
-ethmoidal sinus
-nasal structures
Infratrochlear nerve is the __________ and receives input from:
Terminal branch of V1
-medial canthus/eyelids
-superior palpebral conjunctiva
-bridge of nose
Hutchinson sign
-herpes zoster (HZV) lesion on the tip of the nose
-signals that the virus is also in proximal innervated structures (cornea and uvea)
Herpes zoster virus respects the _______________ and often involves which two nerves?
Midline; infratrochlear nerve and external nasal nerve
Which branches of the trigeminal nerve innervate the eyelids?
V1 and V2
Upper eyelid is innervated by:
-lacrimal nerve
-supraorbital nerve
-supratrochlear nerve
-infratrochlear nerve
Lower eyelid is innervated by:
-zygomaticofacial nerve
-infraorbital nerve
-infratrochlear nerve
Frontal nerve passage is just below the….
Roof of the orbit
Frontal nerve branches:
-supratrochlear nerve
-supraorbital nerve
Supratrochlear nerve innervates:
-medial upper eyelid
-palpebral conjunctiva
Supraorbital nerve innervates:
-central upper eyelid
Variations of the supraorbital nerve
Can leave the orbit through a supraorbital canal and exit supraorbital foramen OR travels through a palpable notch
Supraorbital nerve after exiting the supraorbital foramen/notch branches…
Anteriorly and inferiorly to supply upper eyelid
Maxillary nerve pathway:
-through foramen rotundum to enter sphenoid bone
-through pterygopalatine fossa then splits into infraorbital and zygomatic branches
-exits sphenoid bone via inferior orbital fissure
-infraorbital nerve through infraorbital canal and foramen
Zygomatic nerve branches:
-zygomaticotemporal branch
-zygomaticofacial branch
Zygomaticotemporal branch exits through the _________________ and travels posteriorly within the _________________
Zygomaticotemporal foramen, zygomatic bone
Zygomaticofacial exits through the…
Zygomaticofacial foramen
What passses through the common tendinous ring (CTR) and the superior orbital fissure (SOF)?
-oculomotor superior division
-Abducens nerve
-nasociliary nerve
-oculomotor inferior division
What nerves pass through the SOF only?
-lacrimal nerve
-frontal nerve
-Trochlear nerve
-superior ophthalmic vein
-inferior ophthalmic vein
What passes through the CTR and optic canal?
-optic nerve
-ophthalmic artery
Optic canal is located __________ to SOF
Medial
What passes through both SOF and IOF?
-inferior ophthalmic vein
What passes through IOF only?
-infraorbital nerve
-zygomatic nerve
-infraorbital artery and vein
Preganglion of lacrimal gland fibers (GVE) originate from the…
Superior salivatory nucleus
Motor nucleus of facial nerve is the origin for…
SVE fibers
Motor nucleus of facial nerve is located in the…
Reticular formation of the pons
Facial nerve fascicle arcs around _______ nuclei
CN 6
Damage to the reticular formation of the pons can lead to ________________ and why
Damage to CN 6 and 7 because they are so close together at that point
Branches of CN 7 that innervate periorbital muscles:
-temporal (frontal) nerve
-zygomatic nerve
-angular nerve
Temporal (frontal) nerve innervates:
-upper lid orbicularis
-frontalis muscle
-corrugater muscle
Zygomatic nerve innervates:
-lower lid orbicularis
Angular nerve is formed by __________ and _____________ nerves
Buccal , zygomatic
Angular nerve innervates:
-procerus
-corrugator
Corneal blink reflex is initiated by…
Touching the cornea
Corneal blink reflex pathway:
- Felt by V1
- Travels to trigeminal spinal nucleus
- Intermediary neuron to ipsilateral and contralateral facial motor nuclei
- SVE to palpebral orbicularis
- BLINK
Blink latency decreases with…
Increased magnitude (speed) of coronal touch
Different blink reflexes:
-corneal
-menace
-dazzle
-acoustic/auditory
Corneal blink reflex:
-tactile stimulation
-afferent V1
-efferent CN 7
Menace blink reflex:
-threatening object
-afferent CN 2
-all relies on visual cortex
-efferent CN 7
Dazzle blink reflex:
-bright light
-afferent CN 2
-reflex = brainstem mediated
-efferent CN 7
Acoustic/auditory blink reflex
-loud sound
-afferent CN 8
-efferent CN 7
Palpebral orbicularis controls what in blink reflexes?
The reflex blink
In blink reflexes, zygomatic branch controls…
Lower lid orbicularis
In blink reflexes, temporal (frontal) branch controls…
Upper lid orbicularis
Primary neuron in axons from the motor cortex in facial innervation descend via….
Corticobulbar tracts
Most corticobulbar tracts…
Cross to the contralateral CN 7 nucleus
Upper facial muscles are innervated by…
BOTH hemispheres of the brain
Lower facial muscles are innervated by…
ONLY contralateral hemispheres
Secondary neuron axons from ipsilateral CN 7 nucleus go to…
Facial muscles
Stroke is a __________ lesion
Supra-nuclear lesion
What is seen in a stroke?
-contralateral muscles of lower face affected
-drooping of mouth
Bell’s palsy is a _________ lesion of the..
Idiopathic lesion of the lower motor neurons of CN 7
What is seen in Bell’s palsy?
-upper and lower ipsilateral facial muscles affected
-drooping of mouth and poor eyelid closure
The autonomic nervous system can be divided into:
Sympathetic and parasympathetic
Sympathetic nervous system is apart of the __________ division and has _____________ receptors
Adrenergic ,adrenergic
Parasympathetic nervous system is apart of the ___________ division and have ___________receptors
Cholinergic, muscarinic
___________ receptors are also found in skeletal muscle
Nicotinic (orbicularis, frontalis, procerus, corrugator)
Types of adrenergic receptors:
-alpha1 Gq
-alpha2 Gi
-beta1, beta2 Gs
Muscarinic receptors:
-M3
-M2
M2 is ______ common in the eye than M3
Less common
Agonist
Replicates action of neurotransmitter
Direct action of agonist
Structurally alike to neurotransmitter and acts on receptor site
Indirect action of agonist
-increases the relative neurotransmitter from nerve
-OR decreases reuptake of neurotransmitter
Antagonist
-decreases release of neurotransmitter
-OR bind to receptor sites preventing neurotransmitter from binding
Parasympathetic fibers leave for the ________________, hitching a ride on _______
Ciliary ganglion, CN 3
Ciliary ganglion is located…
In cone behind the eyeball
Ciliary ganglion governs parasympathetic, so why do sympathetic travel through?
Sympathetic can still travel through, and not synapse
Parasympathetic input to iris sphincter:
- Preganglionic fibers in the EWN of midbrain and synapse in ciliary ganglion
- Postgang fibers leave ciliary gang as short ciliary nerves
- Short ciliary nerves pierce sclera nad travel in suprachoroidal space to supraciliary space to sphincter muscle
- PUPIL CONSTRICTION
Parasympathetic pathway to lacrimal gland: Preganglionic fibers:
- Travel through the interla acoustic meats
- Leave facial nerve via hiatus of facial canal -> greater pterosaurs nerve
- Join with deep pterosal nerve and enter pterygoid canal
- Enter pterygopalatine ganglion and synapse
Parasympathetic pathway to lacrimal gland: postganglionic fibers:
- Leave pterygopalatine ganglion via suspensory nerve
- Join zygomatic nerve
- Communicating nerve
- Lacrimal nerve of V1
- INCREASE IN TEAR SECREtiON AT LACRIMAL GLAND
Preganglionic sympathetic innervation:
- 1st order pregang fibers begin in hypothalamus
- Descend into intermediolateral column/horn region of C8-T2, synasping in the cilia spinal center of budge
- 2nd order pregang fibers leave spinal cord through ventral root
- Travel around the clavicle and across the apex of lung
- Enter then ascend the sympathetic chain
- Synapse in the superior cervical ganglion
Postganglionic sympathetic innervation: innervation to upper lid:
1.Plexus around ICA (enter skull through carotid canal)
2. Join the oculomotor nerve (follow superior divisions to upper eyelid)
3. Innervates superior tarsal muscle -> widened palpebral fissure
Postgang sympathetic innervation: short ciliary nerves:
- Ascend as ICA plexus
- Join nasociliary ganglion
- Ciliary ganglion
- Short ciliary nerves
- Innervate choroidal OR conjunctival vessels
VASOCONSTRICTION
Postganglionic sympathetic innervation: long ciliary nerves:
- Ascend as ICA plexus
- Join nasociliary nerve
- Long ciliary nerves
- Innervate choroidal OR conjunctival vessels
- OR ciliary body and iris dilator
VASOCONSTRICTION
Vasoconstriction occurs with…
Choroidal or conjunctival vasculature
Post ganglion if sympathetic innervation: lacrimal gland:
- Ascend as ICA plexus
- Form deep pterosal nerve
- Join with greater petrosal and enter nerve of pterygoid canal
- Enter pterygopalatine ganglion (no synapse)
- Leave pterygopalatine ganglion via suspensory nerve
- Join zygomatic nerve
- Communicating nerve
- Lacrimal nerve of V1
- DECREASE IN TEAR SECRETION
In the end, sympathetic innervation of the eye includes:
-iris dilator muscle
-mullers muscle
-conjunctival/chorodial vessels
-facial/forehead sweat glands
Muller’s muscle function
Helps lift upper lid and widens palpebral fissure
Horners syndorme
Unilateral lesion to one of the sympathetic neurons (central, pregang, or postgang)
Horners syndrome results in:
-ipsilateral ptosis (no muller’s muscle innervation)
-ipsilateral pupil constriction (no iris dilator innervation)
-ipsilateral lack of facial/forehead sweat (no sweat gland innervation)
Horner’s syndrome can be secondary to:
Pancoast tumor (superior pulmonary sulcus tumor)
Presentations of horners syndrome CAUSED BY pancoast tumor:
-shoulder pain (also head and neck, arm, scapula, or anterior crest)
-weakness and atrophy of hand muscles
-ipsilateral Horner syndrome
Pupillary light reflex
-Retinal ganglion cells from retina to pretectal nuclei
-then to EWN, them ciliary ganglion
-from ciliary ganglion to iris sphincter, causing pupil to constrict
Near reflex
Retinal ganglion cells from retina to LGN to primary visual cortex
-take CN 3 to MR to cause convergence
-go to EWN to ciliary ganglion to cause ciliary muscle to accommodate and pupillary sphincter to constrict
Near response involves ________ control
Supranuclear control
Supranuclear control in the near response has diffuse cortical locations including:
-Brodmann area 19 (extra-striate cortex)
-brodmann area 8 (frontal eye fields)
Near response signals converge on…
Rostrum superior colliculus near the pretectal nuclei involved BUT more ventral that pretectal nuceli of light pathway
Argyll Robertson
Lesion to dorsal midbrain that affects fibers from pretectal nuceli and EW light pathway
*more ventrally located near pathway is unaffected
Symptom of argyll Robertson
Light-near dissociation
Adie’s tonic pupil
-Lesion of the efferent pupillary pathway (usually ciliary ganglion of short ciliary nerves)
Adie’s tonic pupil symptoms:
-poor (slow) accommodative reflex
-cholinergic denervation hypersensitivity (very low dose parasympathetic agonist will cause constriction in tonic pupil only)
Pupil size reflects the balance of ____inputs
ANS
Hippus
Small bilateral ongoing pupil size fluctuations NOT due to change sin illumination, fixation, or mood
Sympathetic system controls the _____________ while parasympathetic controls the ____________
Iris dilator, iris sphincter
Physiological anisocoria
-benign condition
-same difference in pupil size between eyes in light vs. dark conditions
-*pupils still routine and reactive to light and accommodation
